With the increasing emphasis on soil conservation practices, including governmental requirements that mandate leaving a certain percentage of crop residue on the surface of the field before, during and after planting operations, there is an increasing challenge on the part of farmers and farm equipment manufacturers alike to provide equipment and farming practices that will comply with these needs and governmental standards. The assignee of the present invention has long been a strong advocate of low tillage planting practices and has been a pioneer in providing equipment to the farming industry for carrying out those practices. Some early examples of the equipment provided by applicants' assignee are depicted in U.S. Pat. Nos. 3,718,191; 4,295,532; 4,425,973; and 4,483,401, where obliquely disposed trash clearing discs are strategically positioned ahead of the planter units to clear narrow strips of bare soil and facilitate seed deposit.
More recently, others in the industry have developed planter attachments which are designed to engage a narrow band of the surface residue and move it aside without disturbing the soil beneath the residue through cultivation or lateral displacement. Examples of the latter type of non-cultivating devices are disclosed in U.S. Pat. Nos. 4,785,890 and 5,076,180.
However, one problem with the non-tilling devices is that while the cleared strip or band of soil may be more accessible to the planter opener in one sense because the residue has been largely cleared away, the soil itself has not been made more receptive to being opened up by the planter. In some cases, there may even be a ridge or peak formed down the middle of the row by the residue clearing devices which must somehow be negotiated by the opener as it prepares the slit or seed receiving trench. As a consequence, the seed placement itself is rendered inaccurate and imprecise, sacrificing the ultimate yield. Conversely, if some conventional units are set deeply enough to eliminate the formation of a ridge or peak down the middle of the row, they may literally dig and throw the soil out of the middle to form a furrow or trench, instead of moving only residue.